INFLUENCE OF ENVIRONMENT 35§ 



gradually lose their black color becoming more 

 yellow, and their young continue to grow more 

 yellow until finally almost all black may dis- 

 appear. The offspring of such salamanders 

 are said to be more yellow than normal; but 

 this also may be an after effect or "induction" 

 which would soon disappear under usual 

 conditions. 



Probably such cases are not instances of true 

 inheritance ; they do not signify a change in the 

 hereditary constitution but an influence on the 

 germ cells of a nutritive or chemical sort com- 

 parable with what takes place when fat stains 

 are fed to animals; the eggs of such animals 

 are stained and the young which develop from 

 such eggs are also stained, though the germi- 

 nal constitution remains unchanged. The 

 very fact that the changed condition is reversi- 

 ble and that it disappears within a short time 

 is evidence that it is not really inherited. 



In conclusion: (1) Developed characters, 

 whether "acquired" or not, are never transmit- 

 ted by heredity, and the hereditary constitu- 

 tion of the germ is not changed by changes in 

 such characters. (2) Probably environmental 



